Finish off European flag (4)
I believe the answer is:
iris
'flag' is the definition.
(type of iris flower)
'finish off european' is the wordplay.
'finish off' means to remove the last letter.
'european' becomes 'Irish ' (Ireland is in Europe).
'irish' with its last letter taken away is 'IRIS'.
(Other definitions for iris that I've seen before include "Goddess of the rainbow in the eye" , "Flag - surrounding pupil" , "bit of mince pie" , "Flower and eye membrane" , "Plant with sword-shaped leaves" .)